It makes the writing, reading, refactoring, testing, instrumentation and stubbing of function specs easy; introduces a concise syntax for inline fspec definitions; helps keep track of side effects; and makes general debugging almost fun, with full evaluation tracing of function I/O, local bindings and all threading macros.
It's Alpha software and the Clojure port, while essentially functional, still needs some love to achieve full feature parity with ClojureScript – most prominently missing at the moment is the tracing functionality.
To steal a quote from Nathan Marz' Specter in a blatant attempt at a so far likely undeserved comparison to its indispensability, I like to think of Ghostwheel as clojure.spec's missing piece. It has become quite essential to me and I hope that you will find it useful too.
Feedback, PRs, and issue reports are welcome and much appreciated.
Do your thing, HN.
Looks like a great project!
Thanks!
There may be some limitations on this compared to using inline gspecs – I have to play around with it a bit, but I think it should work fine. Until then, you can still use Ghostwheel for tracing and side effect detection though.
EDIT: I'll update the docs to make this clearer.
Basically, the macro system makes it possible to extend the language in userspace via libraries. This allows the core language to stay small and focused, while different ideas can be tried out as usage patterns change.
The way Clojure is used today is very different from the way it was used a decade ago. However, the language itself has stay remarkably focused over time.
The core language of Clojure is pretty small and simple compared with most other languages.
I wouldn't see this as some sort of development in Clojure though and I don't really know if that's what cutler meant anyway. Maybe he'll elaborate.
-> →
=> ⇒
>= ≥
I guess those could be considered additional syntax, but they're also completely optional and interchangeable with the corresponding, more Clojure-like keywords.
core.typed still seems to be quite experimental and not yet production-ready, but it certainly looks very promising and I'm keeping an eye on it. It currently also doesn't work on ClojureScript, which has been the primary platform for Ghostwheel so far.